Concrete Slab

Questions, comments and suggestions about the Design Navigator R-value calculator

Concrete Slab

Postby Wallaby.Joe » Fri Aug 05, 2016 11:28 am

Im an Aussie designing a house for a cobber of mine over in New Zealand.
He tells me that any concrete slab, on the ground, of any size, will have a minimum r value of R1.3. Using you calculator I can't get it to replicate his suggested value of 1.3. If the slab is as you calculator what would the best way of raising the value from R1.05 to 1.3.

Cheers Joe.
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Joined: Fri Aug 05, 2016 11:19 am

Re: Concrete Slab

Postby Albrecht Stoecklein » Fri Aug 05, 2016 9:20 pm

Good question, Joe,

Yes it is correct that the NZ Building Code allows you to assume an R-value of R-1.3 for any slab on the ground. So irrespective of the actual R-value you are allowed to use that value in your H1 calculations.


In the DesNav calculator the easiest way to do that is that instead of doing the actual slab floor calculation you simply use R-1.3 as a custom R-value. The DesNav reports include a corresponding note already, but if you want to make sure that the BCA does not ask questions you could additionally add a separate comment in the report.


I hope that helps.

Sunny regards

Albrecht Stoecklein
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Joined: Sat Jun 13, 2009 5:30 pm

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